Displacement nut for a lifting device, and corresponding lifting device

ABSTRACT

A motion nut for a lifting device, especially a car jack, in which a basic body has an internal thread and a threaded spindle is seated in the internal thread. The basic body together with the internal thread is a single unit component formed of at least two separate material components of different materials. The two separate material components form an internal thread region part and an external part, so that properties of the internal thread region is selectable different from properties of the external part. The properties of the thread being selectable for reduced friction and the properties of the external part being selectable for increased strength and stiffness.

BACKGROUND OF THE INVENTION

The invention relates to a motion nut for a lifting device, especially amechanical car jack, comprising a basic body, which is provided with aninternal thread for seating a threaded spindle.

The EP-B 0320613 relates to a car jack with a platform leg, at which asupporting arm, which can be swiveled about a horizontal axis, is hingedand which is engaged by a threaded spindle, which is mounted at theplatform leg in an articulated fashion with a plastic spindle nut, whichengages, with stud axles, bearing recesses of the platform leg form as ashaped sheet-metal part. A metal bracket is connected positively withthe plastic spindle nut and has, at its ends, the stud axles of thespindle nut in the region of the bearing recesses of the supportingsegments covering the platform leg. Disadvantageously, it may be notedhere that the region, accommodating the threaded spindle, must bereinforced by a further component (metal bracket), structural changesalso having to be made to the plastic spindle nut, so that the twocomponents can be positioned accurately relative to one another.

A similar construction is described in the EP-A 0340551. The spindle nutconsists of a plastic body, which interacts with a metallic reinforcingelement. The reinforcing element comprises a sleeve-like projection ofthe plastic body and is constructed as a sheet-metal ring. The criteria,which apply here, are identical with those already described.

A spindle nut connection can be inferred from U.S. Pat. No. 2,664,023.The region of the spindle nut is formed here by a two-part sleeve, thetwo parts of which are connected together by means of a spring elementand over which a one-part bushing, having an internal contourcorresponding to the sleeve accommodation region, is pushed later on.Aside from the tolerances, which must be maintained here between thethreaded spindle and the divided, threaded nut, this type of structuralconfiguration of a motion nut must be regarded as cumbersome andcomponent-intensive.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to develop a motion nut for alifting device which, while simple to construct, nevertheless has goodsliding and friction properties in the spindle region and, at the sametime, ensures an optimum tensile load and torque support in the regionof the lifting device. Moreover, a lifting device, especially amechanical car jack, is to be optimized so that, while having goodsliding and friction properties in the spindle mounting area,nevertheless provides optimum tensile loads and a torque support to thebody of the lifting device, a reduction in the number of components, incomparison to the state of the art, being brought about.

Pursuant to the invention, this objective is accomplished owing to thefact that the basic body is provided as a one-part component, which isformed by at least two material components.

Advantageous further developments of the object of the invention can beinferred from the associated dependent claims.

This objective is also accomplished by a lifting device, especially amechanical car jack, comprising at least one stand element and at leastone lifting element, which are connected with one another over at leastone motion nut, which accommodates a threaded spindle, and, optionally,a counter-bearing, the motion nut being formed by at least two materialcomponents.

For the advantageous developments of the inventive lifting device can beinferred from the associated the dependent claims.

The object of the invention preferably is used for mechanical car jacks,other application cases in the area of motor-driven lifting devices alsobeing conceivable. Due to the inventive object, additional reinforcingelements become dispensable, so that new customer requirements withregard to higher grade static stresses as well as increased dynamicstresses can be realized without problems and the operator comfort ofthe state of the art is retained. Compared to the state of the art,installation space and costs are also not increased.

The object of the invention combines the functions of

-   nut-spindle mounting and sliding-   force and torque support

Materials with a low coefficient of friction book, such as plastic,bronze and casting, are used for the function of mounting thenut-spindle.

Preferably, materials of high strength, such as filled plastics ormetallic materials, are used to fulfill the function of force and torquesupport.

In its simplest construction, the motion nut consists of a basic body,containing two material components, for example, an internal threadregion, consisting of nylon with carbon fibers, connected with an outernylon part containing glass fibers and surrounding the internal threadregion.

Mechanical car jacks are preferably equipped with such motion nuts, sothat they are enclosed by a circumference of protection. If necessary,more than two material components can also be used; however, this mayhave a slightly disadvantageous effect on the cost situation.

The torsion- and tension-resistant connection of the two partialcomponents (internal thread region and outer part) is brought about, forexample, by longitudinal ribs or by thread-like ribs, which extend inthe circumferential direction and may be integrally molded at theinternal thread region and/or the outer part. Alternative embodiments,namely grooves in this internal thread region and/or outer part, are, ofcourse, also conceivable. All customary cross-sectional variations(round, angular or the like) can be used as profiles for suchgroove-like depressions or ribs.

The object of the invention is distinguished owing to the fact that amaterial with good sliding properties and appropriate strength is usedfor the internal thread region and a material of very high strength andstiffness is used for the outer part.

BRIEF DESCRIPTION OF THE DRAWINGS

The object of the invention is described in the following by means of anexample and represented in the drawing, in which

FIG. 1 shows a mechanical car jack in various lifting positions and

FIG. 2 shows a motion nut for the car jack of FIG. 1 in various views.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The inventive car jack 1 comprises a platform leg 2, which can be setdown on level ground 4 by means of a foot 3. The platform leg 2 isconnected with a pivotable supporting harm 5. A threaded spindle 6extends between the free and region of the platform leg 2 and thesupporting arm 5, a basic body 7, in the form of a motion nut beingprovided on the platform leg side and a counter-bearing 8 being providedon the supporting arm side. The supporting arm 5 can be moved up or downrelative to the platform leg 2 over a crank handle of 9, which isconnected over a connecting piece 10 with the threaded spindle 6.

FIG. 2 shows the inventive motion nut 7 in different views.

The motion nut 7 is formed by a basic body, containing two materialcomponents, namely and internal thread region 11 and an external part 12surrounding the internal thread region 11. The latter contains theinternal thread 13, which accommodates the threaded spindle 6, and isproduced by injection molding form a nylon containing a proportion ofcarbon fibers. Rib-like projections, on the one hand, in the form ofribs 15 extending in the longitudinal direction, and as thread-likeprofiles 16, extending in the peripheral direction, are integrallymolded to the outer periphery 14 of the internal thread region 11. Theouter part 12, which is molded in a second step, for example, byinjection molding, about the internal thread region 11, consists ofnylon with a proportion of glass fibers. The rib-like projections 15, 16accordingly form a connection, resistant to torsion and tension, betweenthe two partial components 11, 12. The material, selected for theinternal thread region 11, ensures the mounting and sliding function ofthe nut-spindle, whereas the material, selected for the outer part 12,ensures the force and torque support, for example, at the platform leg2.

The selection of other materials, depending on the case for which theyare to be used, is also conceivable. Alternatively, bronze or castalloys can be used for the internal thread region 11. Furthermore, aplastic with an alternative reinforcing material, such as carbon fibers,aramide, mineral fibers or metal fibers, can be used as material for theinternal thread region 11. Alternatively or additionally, lubricantssuch as PTFE, graphite, silicone, or PE can be admixed with the plastic.

Reinforcing materials, such as fibers of glass, carbon, aramide, boron,ceramic, and/or fabric can be added to the outer part 12.

The distance between the profile, extending in the peripheral direction,extends here approximately to the lead of the internal thread 13.

List of Reference Symbols

-   1. car jack-   2. platform leg-   3. foot-   4. ground-   5. supporting arm-   6. threaded spindle-   7. motion nut-   8. counter-bearing-   9. jack handle-   10. connecting piece-   11. internal thread region-   12. outer part-   13. internal thread-   14. outer periphery-   15. ribs-   16. thread-like profiles

1. A motion nut for a lifting device, especially a car jack, comprising:a basic body having an internal thread; a threaded spindle seated insaid internal thread; said basic body together with said internal threadbeing a single unit component formed of at least two separate materialcomponents of different materials comprising an internal thread regioncomponent part and an external part, so that properties of said internalthread region being selectable different from properties of saidexternal part, said properties of said thread being selectable forreduced friction and said properties of said external part beingselectable for increased strength and stiffness.
 2. The motion nut asdefined in wherein claim 1, wherein said internal thread region issleeve-shaped and formed of filled plastic.
 3. The motion nut as definedin claim 1, wherein said internal thread region is sleeve-shaped andformed of a bronze alloy.
 4. The motion nut as defined in claim 1,wherein said internal thread region is sleeve-shaped and formed of nylonmaterial with a specific carbon fiber content.
 5. The motion nut asdefined in claim 1, wherein said external part surrounds said internalthread region for forming said basic body, said external part comprisinga high strength material.
 6. The motion nut as defined in claim 1,wherein said external part of said basic body surrounds said internalthread region and comprises nylon material with a specific glass fibercontent.
 7. The motion nut as defined in claim 1, wherein said internalthread region and said external part are of injection-molded plastic,said internal thread region being sleeve-shaped and surrounded by saidexternal part.
 8. The motion nut as defined in claim 1, including meansfor preventing rotation between said internal thread region and saidexternal part.
 9. The motion nut as defined in claim 8, wherein saidmeans for preventing rotation between said internal thread region andsaid external part comprising rib-shaped projections in a longitudinaldirection of said internal thread region.
 10. The motion nut as definedin claim 9, wherein said rib-shaped projections are in rounded orangular form.
 11. The motion nut as defined in claim 1, wherein saidinternal thread region is formed of plastic containing lubricants. 12.The motion nut as defined in claim 1, wherein PTFE is included as alubricant.
 13. A lifting device, especially a mechanical car jack,comprising: at least one stand member and at least one lifting member; abasic body formed by a motion nut and a counter bearing and connectingsaid stand member with said lifting member; a threaded spindle receivedby said basic body; said motion nut having at least two separatematerial components of different materials and comprising an internalthreaded region and an external part, so that properties of saidinternal thread region being selectable different from properties ofsaid external part, said properties of said thread being selectable forreduced friction and said properties of said external part beingselectable for increased strength and stiffness.
 14. The lifting deviceas defined in claim 13, wherein said internal thread region is formed ofplastic with a specific carbon fiber content and is surrounded by saidexternal part formed of plastic with a specific glass fiber content. 15.The lifting device as defined in claim 13, wherein said internal threadregion comprises nylon with a specific carbon fiber content and saidexternal part comprises nylon with a specific glass fiber content, saidmotion nut being formed by said internal thread region and said externalpart.
 16. The lifting device as defined in claim 13, including means forpreventing rotation between said internal thread region and saidexternal part and comprising rib-shaped projections.
 17. The liftingdevice as defined in claim 13, wherein said motion nut comprises aninjection-molded part.
 18. The lifting device as defined in claim 13,wherein said internal thread region is formed of plastic containinglubricants.
 19. The lifting device as defined in claim 18, wherein PTFEis included as a lubricant.
 20. A motion nut for a lifting device,especially a car jack, comprising: a basic body having an internalthread; a threaded spindle seated in said internal thread; said basicbody together with said internal thread being a single unit componentformed of at least two separate material components of differentmaterials comprising an internal thread region component part and anexternal part, so that properties of said internal thread region beingselectable different from properties of said external part, saidproperties of said thread being selectable for reduced friction and saidproperties of said external part being selectable for increased strengthand stiffness; said external part surrounding said internal threadregion and being comprised of injection molded plastic; means forpreventing rotation between said internal thread region and saidexternal part and being formed of rib-shaped projections in alongitudinal direction of said internal thread region, said rib-shapedprojections being rounded or angular-shaped.